TMA Legs

[hachiman]

Hi

Just wondering what peoples formula's are for TMA Legs?
I mean

How many legs you do?
What degree of turn you do on your legs?
And how long distance are your legs?

Thanx

[Dr.Sid]

Best is doing something like Z letter .. more then 90 degrees turns .. and time between legs has to be enough for several lines. Also add some time to TA to turn too, because it takes some time .. for this reason it is good idea to have it extended from about one third, so it does not lag that much. You mostly do TMA legs when you only have the contact on TA, so this is important.

If you have the contact on other arrays too, try to extend TA as much as possible, it will allow you to triangulate from two arrays and you get quite good range estimate without full TMA.


Full Z is optimal .. to move target from one side of the boat to the other side is usually enough .. sometimes even slight course changes allows you do TMA quite right.

[hachiman]

Thanx Sid

[Sonoboy]

Go to subguru.com and watch my video TMA: An Accurate Solution (I couldn't think of a better name for it). It will show you how to do what was said above.

[hachiman]

Go to subguru.com and watch my video TMA: An Accurate Solution (I couldn't think of a better name for it). It will show you how to do what was said above.

Hi Sonobuoy.

Actually it as in response to your video i asked this question.
Thanx for the Video and it really helps.
I just wanted more info on the "Z" itself.

[SeaQueen]

If I've decided to try to get an Ekelund range, usually 5-6minute legs are good enough. I usually do a 30-60 degree turn. It makes my math easy. My whole world is 30-60-90 triangles. :know:

If I'm using DEMON to determine range, I will point as close to the target as I can without losing him in the forward end fire to determine his direction of relative motion. 5-6 minutes is good. I try to get 3 line of bearings, and then update it from there. Sometimes I use this technique without DEMON and just guess at the speed. It usually gets close enough provided you pick something reasonable.

Another thing I use a lot, is to just go from a lag to an overlead course, and get the minimum and maximum possible ranges. Just being able to bound his range is usually enough to shoot on. Knowing that, I usually guess that he's someplace close to the average of the two.

The thing about TMA is that while being very accurate is definitely helpful and increases your torpedo effectiveness, for the purposes of shooting, it's good enough to just be close (within a mile or two) because the torpedo's seeker will take care of your area of uncertainty. Just on the basis of search rate, an ADCAP torpedo is one of the most powerful sensors in the game. Because of that, I'd say that unless you're just fascinated by the mathematics of it all, you don't need to obsess over getting the absolute most perfect solution.



Just wondering what peoples formula's are for TMA Legs?
I mean

How many legs you do?
What degree of turn you do on your legs?
And how long distance are your legs?

Thanx

[Bellman]

I agree with much that has been said above paricularly as it it applies to opposing the AI or unwary MP sub skippers.

However in MP sub v sub torp engagements are unrealisticaly* longer ranged and require raising tactical considerations above the mechanistic. It is not IMO appropriate to fixate on rigid TMA procedures. More a flexible approach requires course adjustment/s to place target in a beamed lag relative position whilst building the picture.

Injudicious change of course as prescribed in zig-zagging could take you from lag to lead throwing an anchor line** on the wary opponents TMA display. This will give away your specific range. The problem, at greater ranges, is that in pursuit of lag you hold a broadly reciprocal course and therefore are opening range. A carefull assessment of means of masking your risky turns and range reduction have to be devised. (Topography, layer, neutrals etc.) ***

Initiating TMA techniques should be secondary to good tactics.Much depends on your take on your degree of stealth/surprise and opponents skill/ability to prosper from any careless 'dancing' moves.

Edits:
* 'Knife fights' 1 - 4 nm it is claimed are 'realistic.'
** Construct your own scenario to observe the 'anchor line' range giver.
*** OR just gamble !! Sometimes you have to make a trade-off - giving to get ! Egs. change layer, speed and course early before he catches on !

[Dr.Sid]

Your turns should make it harder for opponent, not easier .. I don't get this ..

[Bellman]

Your thinking defensively !

I hope that we are talking positive aggressive TMA to achieve an accurate firing solution. Nobody said no turns - just dont give anything away easily (''injudicious') 'before you assess which tacking course/s (zig-zagging) will get you a solution before he does.

Yep there is a time and place for screwing his solution with speed, depth and course changes. I just like to send my fishes first on the money then I'll worry about fooling his 'solution.' :D

Edit: Anyway I risk predjucing my own MP so wont add any more to these Fleet course techniques . A Seawolf silently moves out into the estuary - to return ?

[hachiman]

Again thanx for replies.

[Sonoboy]

The Z in my video is nothing more than a clear illustration of what I'm doing. You don't have to make it a Z shape.

I think I will go and experiment with the turn giving away range thing.

[Fish]

Your turns should make it harder for opponent, not easier .. I don't get this ..

Perhaps this should make it clear:

CDR_Blackjack_3rd_CTG2|SOAC-SC> we'll baby step into the answer...to make sure you all undestand and appreciate the concept
<CDR_Blackjack_3rd_CTG2|SOAC-SC> you are in a LAG/BEAM LOS with your target
<LTJG_Nexus7_FOO_3rd> ah without bearign 1 cent max.
<CDR_Blackjack_3rd_CTG2|SOAC-SC> and your opponent unwittingly beleives that he is going to mess up your TMA be changing course all over that place.....
<CDR_Blackjack_3rd_CTG2|SOAC-SC> however, he makes a mistake.......
<CDR_Blackjack_3rd_CTG2|SOAC-SC> he changes the LOS on you from a LAG to a LEAD.....
<CDR_Blackjack_3rd_CTG2|SOAC-SC> after you already have LAG DATA on TMA
<CDR_Blackjack_3rd_CTG2|SOAC-SC> now imagine your TMA screen
<CDR_Blackjack_3rd_CTG2|SOAC-SC> you had a nice bearing fan forming with the LAG LOS
<CDR_Blackjack_3rd_CTG2|SOAC-SC> now all of a sudden, a new bearing line drops.....and instead of falling where you expected it should, it falls in the middle of the fan
<CDR_Blackjack_3rd_CTG2|SOAC-SC> everyone picture this?
<LT_Foca_16th> aye
<LTJGWayne69> aye
<LTJG_Nexus7_FOO_3rd> aye
<LTJG_Apollo_3rd> aye
<CDR_Whitey_Mack> i do
<CAPT_CR_7th_FCO_TO> aye
<CDR_Blackjack_3rd_CTG2|SOAC-SC> ok, now where that new line...and the last line you had (before he changed course to a LEAD) intersect is his approximate new range
<CDR_Blackjack_3rd_CTG2|SOAC-SC> which is called an ANCHOR RANGE
<CDR_Blackjack_3rd_CTG2|SOAC-SC> typically, his actual range will be slightly up/down range from the interesection depending on the LOS you were in to begin with
<CDR_Blackjack_3rd_CTG2|SOAC-SC> so, the instant that he changed course to a lead, he was going 0 knots.....relative....because he had no bearing rate in the LOS
<CDR_Blackjack_3rd_CTG2|SOAC-SC> for that split second, he was all stop
<LTJG_Apollo_3rd> !
<LTJG_Nexus7_FOO_3rd> diw lol
<CDR_Blackjack_3rd_CTG2|SOAC-SC> and that new ANCHOR RANGE represents his true range...because he wasn't moving (relative) at that moment...and for a statoinary target, X always marks the spot in TMA
<CDR_Blackjack_3rd_CTG2|SOAC-SC> right, diw
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LTJG Apollo
<LTJG_Apollo_3rd> what would happend when he ordered instead of turn his course just to go back emergrncy ?
<LTJG_Apollo_3rd> emergency back without turninmg his sub
<CDR_Blackjack_3rd_CTG2|SOAC-SC> same thing....why anyone would do that, I have no idea...lol...but same princple...though it would take a little longer to see it on TMA than a turn
<LTJG_Nexus7_FOO_3rd> !
<CDR_Blackjack_3rd_CTG2|SOAC-SC> remember, TMA is a relative application.....the speeds are relative...not absolute
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LTJG Nexus
<LTJG_Nexus7_FOO_3rd> in an akula or 688 he would break his TA i think (if extended), in a SW also ?
<CDR_Blackjack_3rd_CTG2|SOAC-SC> yea, he would..lol
<CDR_Blackjack_3rd_CTG2|SOAC-SC> both boats
<CDR_Blackjack_3rd_CTG2|SOAC-SC> a backing bell is not good for the TA....in this game or real life
<CDR_Blackjack_3rd_CTG2|SOAC-SC> now, ANCHOR RANGE will be discussed in great detail next class....as it is crucial for determining a TARGET ZIG.....
<CDR_Blackjack_3rd_CTG2|SOAC-SC> however, I thought you guys would like to know of this TMA exploit now
<LTJG_Apollo_3rd> tell us please sir
<CDR_Blackjack_3rd_CTG2|SOAC-SC> and it yields an interesting point....this is why you only do data legs in the same LOS...(i.e. LAG)...with +/-30 degree course changes
<CDR_Blackjack_3rd_CTG2|SOAC-SC> you DO NOT what to change LOS to a LEAD on me during combat....
<CDR_Blackjack_3rd_CTG2|SOAC-SC> no no no no
<LTJG_Nexus7_FOO_3rd> rofl
<CDR_Blackjack_3rd_CTG2|SOAC-SC> you will give me an interest range to your boat...assuming I don't have it already
<CDR_Whitey_Mack> lol
<CDR_Blackjack_3rd_CTG2|SOAC-SC> so, the next time you are diving against an opponent, and he changes a LOS to you.....you have his range...
<CDR_Blackjack_3rd_CTG2|SOAC-SC> you don't have his course....unless your solution was good to begin with
<CDR_Blackjack_3rd_CTG2|SOAC-SC> and we will discuss that next class
<CDR_Blackjack_3rd_CTG2|SOAC-SC> but this is a quick way to get range if your opponent makes this very very common mistake
<CDR_Blackjack_3rd_CTG2|SOAC-SC> so, I have a great question for all of you
<CDR_Blackjack_3rd_CTG2|SOAC-SC> what if you are in a LEAD with me to begin with....and you know you have to go to a LAG, to get an accurate solution....but you also know that turning will give me your range....WHAT WILL YOU DO?
<CDR_Whitey_Mack> LOL
<CAPT_CR_7th_FCO_TO> lol head directly to your bearing fast lol
<LTJGWayne69> good question
<LTJG_Nexus7_FOO_3rd> mhh
<CDR_Blackjack_3rd_CTG2|SOAC-SC> think about it.....because it will happen...
<LTJG_Apollo_3rd> !
<CDR_Whitey_Mack> alot
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LTJG Apollo
<LTJG_Apollo_3rd> in would fier an fish at your possible direction and let you change your course
<LTJG_Apollo_3rd> going fishing
<LTJG_Apollo_3rd> so that i donty need to chnage my course
<CDR_Blackjack_3rd_CTG2|SOAC-SC> ok..lol...so you are goign to get me to change course
<CDR_Blackjack_3rd_CTG2|SOAC-SC> anyone else?
<LTJG_Nexus7_FOO_3rd> better thing is to have opp changing course for me :)
<CDR_Blackjack_3rd_CTG2|SOAC-SC> ok, so you both will sacrifice the time required to gain an effective firing solution....and wait for me to change course...
<CDR_Blackjack_3rd_CTG2|SOAC-SC> anyone else?
<CDR_Blackjack_3rd_CTG2|SOAC-SC> remember, you have NO IDEA what my range is ..... there is no way for you to know that in a LEAD
<LTJG_Nexus7_FOO_3rd> !
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LTJG Nexus
<LTJG_Nexus7_FOO_3rd> nothing sorry
<LT_Foca_16th> !
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LT Foca
<LT_Foca_16th> change speed and turn in LAG
<LTJG_Nexus7_FOO_3rd> !
<CDR_Blackjack_3rd_CTG2|SOAC-SC> aye....it's ultimately up to each of you....but in my opinion (only an opinion), I think it is foolish to wait....I myself, would turn into a LAG immediately...I want a firing solution as quickly as possible
<CDR_Blackjack_3rd_CTG2|SOAC-SC> and the game is about giving something to take something
<CDR_Blackjack_3rd_CTG2|SOAC-SC> LTJG NExus
<LTJG_Nexus7_FOO_3rd> i was thinking about changing course going perpendicular to the to the bearing lines enanching distance for 2 min then turn
<CDR_Blackjack_3rd_CTG2|SOAC-SC> in order to get some LEAD data...then gain some LAG data?
<CDR_Whitey_Mack> CDR BJ, did you explain to them the concept of "PROSECUTION WITH EXTREME PREJUDICE"
<CDR_Blackjack_3rd_CTG2|SOAC-SC> well, remember...you will have to have 2 minutes of LEAD DATA to begin with....to know that you are in a LEAD
<LTJG_Nexus7_FOO_3rd> in order to produce no crossing lines i thought...
<CDR_Blackjack_3rd_CTG2|SOAC-SC> lol..getting to that CDR
<CDR_Blackjack_3rd_CTG2|SOAC-SC> well, a LEAD will have no crossing lines...no bearing fan...as such, you will never get an accurate solution in a LEAD...and as I said...it will take you 4 minutes (two sets of lines) to find you you are in a LEAD...
<CDR_Blackjack_3rd_CTG2|SOAC-SC> however, you can effectively use LEAD data.....once you are in a LAG...and gaining LAG data
<CDR_Blackjack_3rd_CTG2|SOAC-SC> all a LAG does is elminate the variables of course and range in TMA
<CDR_Blackjack_3rd_CTG2|SOAC-SC> narrows down the possibilities for a straight dot stack
<CDR_Blackjack_3rd_CTG2|SOAC-SC> as CDR WM hinted at though...in response to the qeustion posed earlier
<LT_Foca_16th> !
<CDR_Blackjack_3rd_CTG2|SOAC-SC> your job...is to prosecute your target with extreme prejeduice.....your job is not to hide and wait to be engaged
<CDR_Blackjack_3rd_CTG2|SOAC-SC> he who achieves an accurate picture of the battefield first is always, ALWAYS, favored to win......because knowledge is power

[Dr.Sid]

Hm ! Interesesting .. must try that .. this calls for change in my tactics .. I play mostly against AI anyway.

[Fish]

Hm ! Interesesting .. must try that .. this calls for change in my tactics .. I play mostly against AI anyway.
Blackjack was a officer on a US submarine in real live.

[Dr.Sid]

I've just played few missions against AI and this is really helpful .. anytime target is going from lead to lag (or vice-versa), the place where LOBs crosses is very very close to the place where the target really is.

With lead situation LOB's crossing means maximum range .. with lag it means minimum range .. on transition it means exact range. It can really be deadly in MP I guess, especially if your contact tries to change from lead to lag by itself to get his TMA better.

[Fish]

I've just played few missions against AI and this is really helpful .. anytime target is going from lead to lag (or vice-versa), the place where LOBs crosses is very very close to the place where the target really is.

With lead situation LOB's crossing means maximum range .. with lag it means minimum range .. on transition it means exact range. It can really be deadly in MP I guess, especially if your contact tries to change from lead to lag by itself to get his TMA better.

Don't tell others... shhhh. :cool:

[goldorak]

Very interesting :|\\ , are there some publicly available books that treat those issues about TMA and more in general modern naval tactics and/or strategy ?
You know, books available on amazon, etc... ?

[Bill Nichols]

Some great discussion going on here, keep it up!

The link below is to testimony given by CO of USS Greeneville following that sub's collision with and sinking of a Japanese civilian ship. There are some interesting comments about TMA in here!

http://edition.cnn.com/SPECIALS/2001/sub.collision/session3.5.html

and

http://www.cnn.com/SPECIALS/2001/sub.collision/session5.2.html



Also, if you haven't seen this before it's well worth the download:

http://www.haptonstahl.org/ppt/tma_files/frame.htm

:arrgh!:

[Dr.Sid]

Nice reading ! Hey, Bill .. have you ever posted some useless post ? :up:

[Bill Nichols]

All posts are useless in the big scheme of things :|\\

Here's how TMA is described in the BBC's Guide to Submarine Combat:

When you think you have found a submarine, you now need to perform the fire control task of TMA. TMA stands for Target Motion Analysis. Basically try to figure out which direction the enemy sub is moving and how fast it is going. From this you can get an idea of where you need to go to get into a good intercept position.

The recommended tactic is to get around in front of the enemy, than stop and wait, listening as he slowly passes by you. You should then have a good fix on his range, bearing, and mark (where he is and where he is going). You will also be behind him, which means he can't hear you as well, because his sonar is up front and his noisy propeller (called a screw) is between the sonar and you. He will also have to turn around to be able to shoot at you, so it looks like you've got the drop on him (See Note 4). You can then begin to press an attack, assuming you have authorization. Let's just say you have been tasked to terminate with extreme prejudice, so it's time to get it on. Load a fish into tubes 2 and 4. Basically, take your shotgun and load a couple shells. You already have a firing solution (where to put your fish to turn your opponent into fish food) on the target, so now you'll need to flood the torpedo tube. To do this, work the slide to chamber a round. The sound should make you cringe, and with good reason, because you've probably alerted your prey to your existence, position, and intentions. Which means you have only seconds to attack before he attempts a snap shot at you.
Blast a shot in your enemy's direction, while trying to listen to what he is doing. He should be accelerating to full speed (running like a wuss) while turning out of the way and hoping that all this running and turning puts you in range of return fire. So you should turn away from him and run to try and get out of range of his fish. And try to restrain the desire to shout "Conn, sonar! Crazy Ivan!" It's not a Crazy Ivan, and it won't help you to stay hidden. You don't have to worry about him playing a fantastic game of underwater chicken and having the fish swing around and hit you, enabling your pretentious Executive Officer to berate you for being arrogant and killing you. This just doesn't happen. In real life, because shotgun shells have no homing capabilities, being purely ballistic weapons, and in submarine warfare, because torpedoes are quite crafty and will click off if they find they have turned around. They then sink harmlessly to the sea bottom, to be exploded years later by a hapless scuba diver.


Read the entire BBC guide here:

http://www.subguru.com/BBC-Guide.htm

:sunny:

[Henson]

As an instructor of FTOWs and junior OODs, the Greenville transcripts make me ill. I can see this stuff happening sooo many times in my trainers, and on some level it's OK for it to happen in a safe environment where we can correct the root deficiencies, but in this case relatively obvious information was not noticed and procedures were ignored, and the consequences included several dead students.

This incident literally changed how we do business as a force, and things changed for the better. Thanks for the link, it'll make a long night's reading for me.

[SeaQueen]

Naval Operations Analysis by Danial Wagner is a text book used in the mathematics department at the US Naval Academy. Although it's not for the mathematically challenged (calculus, probabilit, statistics, and game theory are used freely throughout the book), it contains instructions on how to do Ekelund and Speiss TMA.

They have a whole chapter on bearings only TMA and the mathematics behind it, as well as the reasoning behind positioning combat air patrols, search, weapons effectiveness, etc. It's interesting because occaisionally for examples and problems it'll use historical data to explain why things were done the way they were. He also does a lot of stuff that is also in Koopman's Search and Screening but with greater clarity. All the stuff on barrier patrols and the random search equation that's in Koopman are reproduced in Wagner.

Very interesting :|\\ , are there some publicly available books that treat those issues about TMA and more in general modern naval tactics and/or strategy ?
You know, books available on amazon, etc... ?

[sonar732]

As an instructor of FTOWs and junior OODs, the Greenville transcripts make me ill. I can see this stuff happening sooo many times in my trainers, and on some level it's OK for it to happen in a safe environment where we can correct the root deficiencies, but in this case relatively obvious information was not noticed and procedures were ignored, and the consequences included several dead students.

This incident literally changed how we do business as a force, and things changed for the better. Thanks for the link, it'll make a long night's reading for me.

I wouldn't doubt that they are going back thru their SOP's again during this current stand down of the submarine force.:damn::damn::o:o